Artificially Engineered Nanostrain in Iron Chalcogenide Superconductor Thin Film for Enhancing Supercurrent

TL;DR

This study demonstrates that introducing nanostrain in iron chalcogenide superconducting thin films via CeO2 injection significantly enhances their critical current density, promising improvements for superconductor applications.

Contribution

The paper presents a novel method to create uniform nanostrain in FST thin films using CeO2 injection, leading to improved superconducting performance.

Findings

Nanostrain induced by CeO2 injection verified by TEM and phase analysis.

Achieved critical current density of 3.5 MA/cm2 at 6 K.

Enhanced Jc under magnetic fields compared to pristine films.

Abstract

Although nanoscale deformation, such as nanostrain in iron chalcogenide (FeSexTe1-x, FST) thin films, has attracted attention owing to the enhancement of general superconducting properties, including critical current density (Jc) and critical transition temperature, its formation has proven to be an extremely challenging and complex process thus far. Herein, we successfully fabricated an epitaxial FST thin film with uniformly distributed nanostrain by injection of a trace amount of CeO2 inside FST matrix using sequential pulsed laser deposition. Using transmission electron microscopy and geometrical phase analysis, we verified that a trace amount of CeO2 injection forms nanoscale fine defects with a nanostrained region, which has a tensile strain (ezz ~ 0.02) along the c-axis of the FST matrix. The nanostrained FST thin film achieves a remarkable Jc of 3.5 MA/cm2 for a self-field at 6 K and a highly enhanced Jc under the entire magnetic field with respect to a pristine FST thin film.